1. Field of the Invention
The present invention relates to a method for producing a Group III nitride semiconductor through the flux method and, more particularly, to a production method realizing effective mixing of a dopant in the molten material.
2. Background Art
The Na flux method is a known method for producing a Group III nitride semiconductor such as GaN. In this method, Na (sodium) and Ga (gallium) are melted and maintained at about 800° C., and gallium is reacted with nitrogen at a pressure of some ten atmospheres, to thereby grow GaN crystals.
For example, Japanese Patent Application Laid-Open (kokai) No. 2008-290929 discloses that addition of silicon (Si) to the molten material in the Na flux method suppresses crystal growth of GaN, and discloses studies on use of germanium (Ge) serving as an n-type dopant.
However, when germanium is added to the material of the flux method, in some cases, an alloy such as GeNa3 is formed from germanium and sodium. Because GeNa3 has a high melting temperature of 820° C. at ambient pressure, Ge is not satisfactorily admixed in a molten mixture of sodium and gallium. That causes raising problems such as variation in Ge concentration of a GaN crystal and generation of a large amount of miscellaneous crystals, leading to a drop in production yield.